Hide Portfolio Thumbnail Title or date

Add this into the Custom CSS box located in your Salient Options panel :

/* hide title and date */
body .portfolio-items .col .work-info .vert-center {
    display: none;
}
/* hide title only */
body .portfolio-items .col .work-item.style-3 h3 {
    display: none;
}
/* hide date only*/
body .portfolio-items .col .work-info .vert-center p {
    display: none;
}<p>Cheers</p>